1. Field of the Invention
The present invention relates to improved lubricant compositions for finishing fibers and filaments wherein the lubricants meet the requirements of the Food and Drug Administration (FDA) for use as indirect food additives.
2. Description of the Prior Art
The need to use processing aids in the manufacture of synthetic fibers and filaments is well known and numerous lubricating finishes have been developed for this purpose. Where the fibers and yarns are used for food packaging materials, the lubricants must meet the requirements of the appropriate Food and Drug regulations.
A finishing composition comprised entirely of ingredients approved for use as direct or indirect food additives and useful for multi-filamentary yarns to be used in food packaging is disclosed in U.S. Pat. No. 3,993,571. The finishing compositions of U.S. Pat. No. 3,993,571 are useful for the treatment of synthetic linear polymer yarns, including polyamides, polyesters and polyolefins and are comprised of 47-53 weight percent butyl stearate or coconut oil, 16-20 weight percent sorbitan monooleate and 30-34 weight percent ethoxylated sorbitan monooleate. Mixtures of glycerol monooleate and ethoxylated sorbitan monolaurate also meet the FDA requirements and have been used by the industry as lubricants for processing fibers to be used for food packaging materials.
While finishes of the above types typically provide acceptable levels of lubrication for polyester and polyamide fibers, they are generally not as effective as finishes formulated using lubricants which are not approved for use as direct or indirect food additives. Moreover, they do not provide acceptable performance characteristics which the more difficulty processable non-polar polypropylene fibers. It would be highly advantageous if a finish, comprised solely of lubricants which meet the FDA requirements for use as indirect food additives were available which provided superior performance characteristics, particularly for polypropylene fibers.